Glass or plastic materials used for windows, mirrors, lenses, goggles, and facial masks or shields become foggy when they are exposed to high humidity and temperature, or used at interfacial boundaries with a large difference in temperature or humidity. Products exposed to such conditions include those used in medical, military and industrial safety applications. Fog is caused by the condensation of moisture on the surface. For example, exhaled air from a person wearing a safety shield could cause fogging. To reduce or eliminate this problem, anti-fog coatings are frequently needed. These typically include hydrophilic materials that overcome fogging by absorbing and releasing moisture from the surface. In many of these applications, it is also important that the coating be substantially transparent and not generate excessive glare, which results from reflection of light. Thus, anti-glare properties are desirable. Anti-glare properties are also of value in making certain optical devices, such as optical retardation plates or polarizing plates, and can for example be used in display devices such as liquid crystal displays.
Anti-glare and anti-fog coatings may also be needed for use on disposable items such as single-use facemasks, which typically are based on polymer film substrates. For these and other applications, it is desirable that cost be kept to a minimum, and therefore in-line application methods would in many cases be desirable in order to keep costs low. However, existing anti-glare and anti-fog compositions capable of providing suitable anti-fog and anti-glare properties are often not easily applied by in-line processes. There is a continuing need for anti-glare and anti-fog coatings, and methods of applying them, capable of addressing these needs.